1. Field of the Invention
This invention relates to a printed circuit board assembly of the type wherein a plurality of electronic parts including a heat generating part are mounted on a printed circuit board, and more particularly to an improved printed circuit board assembly wherein heat generated from a heat generating part is radiated efficiently.
2. Description of the Related Art
In recent years, as high integration of integrated circuits (ICs and LSIs) and high density mounting of electronic parts proceed, the amount of heat generated from a printed circuit board assembly, which is used in electronic apparatus such as communication apparatus, progressively increases, and therefore, stable and efficient heat radiation must be achieved. A popularly known one of conventional structures of a printed circuit board assembly for which a special measure is taken for heat radiation involves a heat radiation fin mounted on an upper face of a package of a heat generating part such as an LSI mounted on a printed circuit board.
This structure, however, is disadvantageous in that the thickness of the printed circuit board assembly is increased by the heat radiation fin and it is difficult to minimize the printed circuit board assembly. Thus, another improved structure has been proposed wherein a through-hole is formed at a portion of a printed circuit board at which a heat generating part is to be mounted and a heat radiation plate made of a metal is mounted on the rear face of the printed circuit board in such a manner as to close up the through-hole and then the heat generating part is fitted into the through-hole to mount the same onto the printed circuit board while a thermal compound is filled between the package of the heat generating part and the heat radiation plate to transmit and radiate heat to and from the heat radiation plate.
Even with the improved structure, however, there is a problem in that the thermal compound filled between the package of the heat generating part and the heat radiation plate is deteriorated as time passes and stable heat radiation cannot be assured for a long period of time. Further, since the heat radiation plate is mounted on the rear face of the printed circuit board, there is another problem in that minimization of the printed circuit board assembly is still difficult due to the thickness of the heat radiation plate. Furthermore, since the through-hole is formed in the printed circuit board and a circuit pattern cannot be formed at the location of the through-hole on the printed circuit board, there is a further problem in that the wiring efficiency of the printed circuit board is low.